1986 TOYOTA SUPRA relay

Engine Coolant Temperature (ECT)
Switch
ECT SWITCH INSPECTION
1. REMOVE ENGINE UNDER COVER
2. DRAIN ENGINE COOLANT
3. REMOVE ECT SWITCH
(a) Disconnect the ECT switch connector.
(b) Remove the ECT switch.
(c) Remove the O±ring from the ECT switch.
4. INSPECT ECT SWITCH
(a) Usin g an oh mme te r, ch e ck th a t th e re is no co n tin u ity
between the terminals when the coolant temperature is
above 97°C (207°F).
(b) Using an ohmmeter, check that there is continuity between
the terminals when the coolant temperature is below 88°C
(190°F).
If continuity is not as specified, replace the switch.
5. REINSTALL ECT SWITCH
(a) Install a new O±ring to the ECT switch.
(b) Apply soapy water to the O±ring.
(c) Install the ECT switch.
Torque: 7.4 NVm (75 kgfVcm, 65 in.Vlbf)
(d) Connect the ECT switch connector.
6. REFILL WITH ENGINE COOLANT
7. START ENGINE AND CHECK FOR LEAKS
8. REINSTALL ENGINE UNDER COVER
No.1 Radiator Fan Relay
(ºRADIATOR FAN RELAYº)
RADIATOR FAN RELAY INSPECTION
1. w/ Auto Spoiler:
REMOVE LH HEADLIGHT
2. w/o Auto Spoiler:
REMOVE ENGINE UNDER COVER
3. REMOVE RADIATOR FAN RELAY
4. INSPECT RADIATOR FAN RELAY
A. Inspect relay continuity
(a) Using an ohmmeter, check that there is continuity between
terminals 3 and 4.
(b) Check that there is no continuity between terminals 1 and 2.
If continuity is as specified, replace the relay. EG±356
± ENGINECOOLING SYSTEM

B. Inspect relay operation
(a) Apply battery voltage across terminals 3 and 4.
(b) Using an ohmmeter, check that there is continuity between
terminals 1 and 2.
If operation is not as specified, replace the relay.
5. REINSTALL RADIATOR FAN RELAY
6. w/ Auto Spoiler:
REINSTALL LH HEADLIGHT
7. w/o Auto Spoiler:
REINSTALL ENGINE UNDER COVER
No.2 Radiator Fan Relay
(ºA.B.S. (TRAC) RELAYº)
RADIATOR FAN RELAY INSPECTION
1. w/ Auto Spoiler:
REMOVE LH HEADLIGHT
2. w/o Auto Spoiler:
REMOVE ENGINE UNDER COVER
3. REMOVE RADIATOR FAN RELAY
4. INSPECT RADIATOR FAN RELAY
A. Inspect relay continuity
(a) Using an ohmmeter, check that there is continuity between
terminals 1 and 6.
(b) Check that there is continuity between terminals 3 and 5.
(c) Check that there is no continuity between terminals 2 and 5.
If continuity is not as specified, replace the relay.
B. Inspect relay operation
(a) Apply battery voltage across terminals 1 and 6.
(b) Usin g an oh mme te r, ch e ck th a t th e re is no co n tin u ity
between terminals 3 and 5.
(c) Check that there is continuity between terminals 2 and 5.
If operation is not as specified, replace the relay.
5. REINSTALL RADIATOR FAN RELAY
6. w/ Auto Spoiler:
REINSTALL LH HEADLIGHT
7. w/o Auto Spoiler:
REINSTALL ENGINE UNDER COVER
± ENGINECOOLING SYSTEMEG±357

2
INTRODUCTION
This manual consists of the following 11 sections:
No.
SectionDescription
A
INDEXIndex of the contents of this manual.
A
INTRODUCTIONBrief explanation of each section.
BHOW TO USE
THIS MANUALInstructions on how to use this manual.
CTROUBLE±
SHOOTINGDescribes the basic inspection procedures for electrical circuits.
DABBREVIATIONSDefines the abbreviations used in this manual.
E
GLOSSARY OF
TERMS AND
SYMBOLS
Defines the symbols and functions of major parts.
FRELAY LOCATIONSShows position of the Electronic Control Unit, Relays, Relay Block, etc.
This section is closely related to the system circuit.
GELECTRICAL
WIRING ROUTINGDescribes position of Parts Connectors, Splice points, Ground points, etc.
This section is closely related to the system circuit.
HPOWER SOURCE
(Current Flow Chart)Describes power distribution from the power supply to various electrical
loads.
INDEXIndex of the system circuits.
I
SYSTEM CIRCUITS
Electrical circuits of each system are shown from the power supply through
ground points. Wiring connections and their positions are shown and
classified by code according to the connection method. (Refer to the
section, ªHow to use this manualº).
The ªSystem Outlineº and ªService Hintsº useful for troubleshooting are also
contained in this section.
JGROUND POINTSShows ground positions of all parts described in this manual.
K
OVERALL
ELECTRICAL
WIRING DIAGRAM
Provides circuit diagrams showing the circuit connections.

3
HOW TO USE THIS MANUAL
This manual provides information on the electrical circuits installed on vehicles by
dividing them into a circuit for each system.
The actual wiring of each system circuit is shown from the point where the power source
is received from the battery as far as each ground point. (All circuit diagrams are shown
with the switches in the OFF position.)
When troubleshooting any problem, first understand the operation of the circuit where
the problem was detected (see System Circuit section), the power source supplying
power to that circuit (see Power Source section), and the ground points (see Ground
Points section). See the System Outline to understand the circuit operation.
When the circuit operation is understood, begin troubleshooting of the problem circuit
to isolate the cause. Use Relay Location and Electrical Wire Routing sections to find
each part, junction block and wiring harness connectors, wiring harness and wiring
harness connectors, splice points, and ground points of each system circuit. Internal
wiring for each junction block is also provided for better understanding of connection
within a junction block.
Wiring related to each system is indicated in each system circuit by arrows (from

, to ). When overall connections are required, see the Overall Wiring Diagram
at the end of this manual.

A
B
C
D
E
F
G
H
I
J
K
L
M
N
O
P
5
:System Title
:Indicates a Relay Block. No shading is used and only
the Relay Block No. is shown to distinguish it from the
J/B.
Example: Indicates Relay Block No. 1.
:Indicates the connector to be connected to a part (the
numeral indicates the pin No.)
Explanation of pin use.
The pins shown are only for the highest grade, or only
include those in the specification.
:Connector Color
Connectors not indicated are milky white in color.
:( ) is used to indicate different wiring and connector,
etc. when the vehicle model, engine type, or
specification is different.
:Indicates related system.
:Indicates the wiring harness and wiring harness
connector. The wiring harness with male terminal is
shown with arrows ( ).
Outside numerals are pin numbers.
The first letter of the code for each wiring harness and
wiring harness connector(s) indicates the component's
location, e.g., ªEº for the Engine Compartment, ªIº for the
Instrument Panel and Surrounding area, and ªBº for the
Body and Surrounding area.
When more than one code has the first and second
letters in common, followed by numbers (e.g., IH1, IH2),
this indicates the same type of wiring harness and
wiring harness connector.
:Represents a part (all parts are shown in sky blue). The
code is the same as the code used in parts position.
:Junction Block (The number in the circle is the J/B No.
and the connector code is shown beside it). Junction
Blocks are shaded to clearly separate them from other
parts (different junction blocks are shaded differently for
further clarification).
3B indicates
that it is inside
Junction Block
No. 3.
Example::Indicates the wiring color.
Wire colors are indicated by an alphabetical code.
B = Black L = Blue R = Red
BR = Brown LG = Light Green V = Violet
G = Green O = Orange W = White
GR = Gray P = Pink Y = Yellow
The first letter indicates the basic wire color and the
second letter indicates the color of the stripe.
Example: L ± Y
(Blue) (Yellow)
:Indicates a wiring Splice Point (Codes are ªEº for the
Engine Room, ªIº for the Instrument Panel, and ªBº for
the Body).
Example:
The Location of Splice Point I 5 is indicated by the
shaded section.
:Page No.
:Indicates a shielded cable.
:Indicates a ground point.
The first letter of the code for each ground point(s)
indicates the component's location, e.g., ªEº for the
Engine Compartment, ªIº for the Instrument Panel and
Surrounding area, and ªBº for the Body and
Surrounding area.
:Indicates the pin number of the connector.
The numbering system is different for female and male
connectors.
Example: Numbered in order
from upper left to
lower rightNumbered in order
from upper right to
lower left
:When 2 parts both use one connector in common, the
parts connector name used in the wire routing section
is shown in square brackets [ ].

Q
R
S
T
U
V
W
X
6
HOW TO USE THIS MANUAL
WITH THE IGNITION SW TURNED ON, THE CURRENT FLOWS TO TERMINAL 3 OF THE POWER WINDOW MASTER SW, TERMINAL 2 OF THE POWER WINDOW CONTROL RELAY
AND TERMINAL 8 OF THE POWER WINDOW SW THROUGH THE DOOR FUSE.
1.DRIVER'S WINDOW ªMANUAL UPº OPERATION BY MASTER SW
HOLDING MANUAL SW (DRIVER'S) ON ªUPº POSITION LOCATED IN POWER WINDOW MASTER SW, THE CURRENT FLOWS TO TERMINAL 5 OF THE POWER WINDOW
CONTROL RELAY THROUGH TERMINAL 3 OF THE MASTER SW TERMINAL 2 TO OPERATE A POWER WINDOW CONTROL RELAY. THUS THE CURRENT INSIDE THE RELAY
FLOWS FROM TERMINAL 2 OF THE RELAY TERMINAL 1 TERMINAL 2 OF THE POWER WINDOW MOTOR TERMINAL 1 TERMINAL 4 OF THE RELAY TERMINAL
3 TO GROUND. THE MOTOR TURNS TO ASCENT THE WINDOW. RELEASING THIS SW, THE ROTATION OF MOTOR IS STOPPED AND THE WINDOWS CAN STOP AT WILL
POINT.
(FOR THE ªMANUAL DOWNº OPERATION, CURRENT FLOWS IN THE REVERSE DIRECTION BECAUSE THE TERMINALS WHERE IT FLOWS ARE CHANGED).
2.DRIVER'S WINDOW ªAUTO DOWNº OPERATION BY MASTER SW
ONCE THE ªAUTO DOWNº BUTTON OF THE MASTER SW IS PUSHED, THE CURRENT FLOWS TERMINAL 9 OF THE POWER WINDOW CONTROL RELAY THROUGH TERMINAL
3 OF THE MASTER SW TERMINALS 8 AND 9 TO OPERATE THE RELAY. THUS THE CURRENT INSIDE THE POWER WINDOW CONTROL RELAY FLOWS FROM TERMINAL
2 OF THE RELAY TERMINAL 4 TERMINAL 1 OF THE POWER WINDOW MOTOR TERMINAL 2 TERMINAL 1 OF THE RELAY TERMINAL 3 TO GROUND.
THE MOTOR CONTINUES THE ROTATION ENABLING TO DESCENT THE WINDOW.
THE WINDOW DESCENDS TO THE END POSITION. THE CURRENT WILL BE CUT OFF TO RELEASE THE AUTO DOWN FUNCTION BASED ON THE INCREASING CURRENT
BETWEEN TERMINAL 2 OF THE RELAY AND TERMINAL 1 IN RELAY.
3.DRIVER'S WINDOW AUTO DOWN RELEASE OPERATION BY MASTER SW
HOLDING THE MANUAL SW (DRIVER'S) ON ªUPº POSITION IN OPERATING AUTO DOWN. THE CURRENT FROM TERMINAL 3 OF THE MASTER SW PASSING TERMINAL 2
FLOWS TERMINAL 5 OF THE RELAY AND RELEASES THE AUTO DOWN FUNCTION IN THE POWER WINDOW CONTROL RELAY. RELEASING THE HAND FROM SW, WINDOW
STOPS AND CONTINUING ON TOUCHING SW, THE FUNCTION SWITCHES TO MANUAL UP OPERATION.
4.PASSENGER'S WINDOW UP OPERATION (MASTER SW) AND WINDOW LOCK SW OPERATION
HOLDING PASSENGER'S WINDOW SW (MASTER SW) ON ªUPº, THE CURRENT FLOWS FROM TERMINAL 3 OF THE MASTER SW PASSING TERMINAL 6 TO TERMINAL 3 OF
THE POWER WINDOW SW (PASSENGER'S) TERMINAL 4 TERMINAL 2 OF THE MOTOR TERMINAL 1 TERMINAL 9 OF THE POWER WINDOW SW TERMINAL
7 TERMINAL 1 OF THE MASTER SW TERMINAL 4 TO GROUND. THE MOTOR RUNS TO ASCENT THE WINDOW. RELEASING THIS SW, THE ROTATION OF MOTOR IS
STOPPED AND WINDOW CAN STOP AT WILL PLACE.
SWITCHING THE WINDOW LOCK SW IN ªLOCKº POSITION, THE CIRCUIT IS OPENED AND STOPPED THE MOTOR ROTATION.
(FOR THE DOWN OPERATION, CURRENT FLOWS IN THE REVERSE DIRECTION BECAUSE THE TERMINALS WHERE IT FLOWS ARE CHANGED).
P 2 POWER WINDOW CONTROL RELAY
3±GROUND: ALWAYS CONTINUITY
2±GROUND: APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION
5±GROUND: APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION AND MASTER SW AT UP POSITION
8±GROUND: APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION AND MASTER SW AT AUTO DOWN POSITION
9±GROUND: APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION AND MASTER SW AT DOWN OR AUTO DOWN POSITION
P 4 POWER WINDOW MASTER SW
4±GROUND: ALWAYS CONTINUITY
3±GROUND: APPROX. 12 VOLTS WITH IGNITION SW AT ON POSITION
WINDOW LOCK SW
OPEN WITH THE WINDOW LOCK SW AT LOCK POSITION
: PARTS LOCATION
CODESEE PAGECODESEE PAGECODESEE PAGE
P 221P 421P 621
P 321P 521
: RELAY BLOCKS
CODESEE PAGERELAY BLOCK (RELAY BLOCK LOCATION)
116R/B NO. 1 (INSTRUMENT PANEL LEFT SIDE)
: JUNCTION BLOCK AND WIRE HARNESS CONNECTOR
CODESEE PAGEJUNCTION BLOCK AND WIRE HARNESS (CONNECTOR LOCATION)
3B14J/B NO. 3 AND COWL WIRE (INSTRUMENT PANEL LEFT SIDE)
: CONNECTOR JOINING WIRE HARNESS AND WIRE HARNESS
CODESEE PAGEJOINING WIRE HARNESS AND WIRE HARNESS (CONNECTOR LOCATION)
ID126FRONT DOOR RH WIRE AND COWL WIRE (RIGHT KICK PANEL)
IH126FRONT DOOR LH WIRE AND COWL WIRE (LEFT KICK PANEL)
: GROUND POINTS
CODESEE PAGEGROUND POINT LOCATION
IC24COWL LEFT
: SPLICE POINTS
CODESEE PAGEWIRE HARNESSES WITH SPLICE POINTS
I 524COWL WIRE
SYSTEM OUTLINE
SERVICE HINTS

Q
R
S
T
U
V
W
X
Junction connector (code: J1, J2, J3, J4, J5,
J6, J7, J8, J9) in this manual include a short
terminal which is connected to a number of
wire harnesses. Always perform inspection
with the short terminal installed. (When
installing the wire harnesses, the harnesses
can be connected to any position within the
short terminal grouping. Accordingly, in other
vehicles, the same position in the short
terminal may be connected to a wire harness
from a different part.)
Wire harness sharing the same short terminal
grouping have the same color.
HINT:
7
:Explains the system outline.
:Indicates values or explains the function for reference during troubleshooting.
:Indicates the reference page showing the position on the vehicle of the parts in the system circuit.
Example: Part ªP4º (Power Window Master SW) is on page 21 of the manual.
* The letter in the code is from the first letter of the part, and the number indicates its order
in parts starting with that letter.
Part is 4th in order
Power Window Master SW Example: P
4
:Indicates the reference page showing the position on the vehicle of Relay Block Connectors in the
system circuit.
Example: Connector ª1º is described on page 16 of this manual and is installed on the left side of the
instrument panel.
:Indicates the reference page showing the position on the vehicle of J/B and Wire Harness in the system
circuit.
Example: Connector ª3Bºconnects the Cowl Wire and J/B No. 3. It is described on page 14 of this
manual, and is installed on the instrument panel left side.
:Indicates the reference page describing the wiring harness and wiring harness connector (the female
wiring harness is shown first, followed by the male wiring harness).
Example: Connector ªID1ºconnects the front door RH wire (female) and cowl wire (male). It is described
on page 26 of this manual, and is installed on the right side kick panel.
:Indicates the reference page showing the position of the ground points on the vehicle.
Example: Ground point ªICº is described on page 24 of this manual and is installed on the cowl left side.
:Indicates the reference page showing the position of the splice points on the vehicle.
Example: Splice point ªI 5º is on the Cowl Wire Harness and is described on page 24 of this manual.

10
TROUBLESHOOTING
VOLTAGE CHECK
(a) Establish conditions in which voltage is present at the
check point.
Example:
± Ignition SW on
± Ignition SW and SW 1 on
± Ignition SW, SW 1 and Relay on (SW 2 off)
(b) Using a voltmeter, connect the negative lead to a good
ground point or negative battery terminal, and the
positive lead to the connector or component terminal.
This check can be done with a test light instead of a
voltmeter.
CONTINUITY AND RESISTANCE CHECK
(a) Disconnect the battery terminal or wire so there is no
voltage between the check points.
(b) Contact the two leads of an ohmmeter to each of the
check points.
If the circuit has diodes, reverse the two leads and check
again.
When contacting the negative lead to the diode positive side
and the positive lead to the negative side, there should be
continuity.
When contacting the two leads in reverse, there should be no
continuity.
(c) Use a volt/ohmmeter with high impedance (10 kW/V
minimum) for troubleshooting of the electrical circuit.